Acetic Acid → 4-[2-[4-(2-Pyridinyl)-1-piperazinyl]ethyl]cyclohexanone

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Reaction Steps

A solution of 1-(1,4-dioxaspiro[4,5]dec-8-yl-acetyl)-4-(2-pyridinyl)piperazine (17.0 g) (Example I) in 500 ml of dry tetrahydrofuran is treated with sodium borohydride (6.81 g) under nitrogen and the resulting suspension is treated dropwise with a solution of boron trifluoride etherate (29.5 ml) in 100 ml of tetrahydrofuran. The reaction mixture is stirred at room temperature overnight. A solution of glacial acetic acid (10.3 ml) in 100 ml of tetrahydrofuran is added dropwise, and the mixture stirred at room temperature for two hours. The solvent is evaporated in vacuo and the residue refluxed with 250 ml of a 10% solution of hydrochloric acid and 250 ml of acetone for two hours. The mixture is concentrated in vacuo to about one-half of the original volume. The remaining aqueous solution is washed twice with ethyl acetate and made basic with ammonium hydroxide. The crude product is extracted into ethyl acetate (2×300 ml). The organic extract is dried over magnesium sulfate and concentrated in vacuo. The reaction mixture is purified by MPLC (silica; 2% methanol, 98% chloroform) to give 9.73 g of the title compound as a colorless solid; mp 104°-106° C.

Provenance & Evidence